I'd like to do some diagnostic checks on Mockobjects and test helpers. How I generate that tests with JUnitDoclet?

Be carefull, explicitly testing of tests could lead to an infinite recursion. We like to think of the test being tested by the application while the tests show the absence of possible errors in the application. After all, that is why in Test Driven Development (TDD) you want to see a test failing first before you make the application pass the test. If you really know what you are doing, pass the "-testintest" option when invoking javadoc. Only then JUnitDoclet will generate TestCases for helper classes in test packages and test trees, but no TestCases for TestCases or TestSuites.